car engineering concept design - mitweb.mit.edu/.../classnotes/14_conceptdesign.pdf · car...

April 1st, 2006 3rd Georgia Tech Auto Show

Car Engineering Concept Design

When setting to the task of conceiving a new car, I remind myselfwhat the basics of an automobile are:

“a self-propelled means of

transporting PEOPLE”

The starting point I use is the PEOPLE needing to be transported

In the Ferrari case, it so far means 1 (racing single seaters), 2, or 4people


Meet OSCAR, the car designer’s manikin:


OSCAR’s “zero” is the so-called H-Point, which corresponds to thehip joint

H-point


Starting from the H-point, the interior space requirements may bedefined:

H-point


The H-Point travels as a result of the seat’s adjustment travelenvelope

H-pointtravelenvelope


If the car we are designing needs a more upright stance, the foot-to-Hpoint vertical distance will increase, while the longitudinal distancewill decrease

H-point


Extreme sports cars need a very reclined stance in order to reducevehicle height; the foot-to-H point vertical distance will decrease,while the longitudinal distance will increase

H-point


Cars with more than one row will derive their overall dimension alsofrom the distance between the rows of seats


Ferraris historically have never had more than two rows


The distance between front and rear row determine the leg space thesecond row will have; this dimension directly influences wheelbase


Once the stance and interior space have been established, thevehicle’s height becomes an almost direct consequence

These consideration are needed in three dimensions (width)

1

23

4


Some basic requirements for cabin entry and exit need to be defined→ door seal limits→ possible door hinge axis


Other vehicle components can now be laid out

Rarely can component characteristics be specified as a vehicle’sconcept progresses; we are usually dealing with a given componentset (engine, transmission, suspension) if not with a complete platform


Wheel positioning is very critical in determining front-to-rear massbias, which in turn affects greatly the vehicle’s three main dynamicareas:

It is a very iterative process; it helps if the general vehicle architecturehas been envisioned before starting, otherwise it will turn into ajourney in the unknown, which is generally unsatisfatory

CORNERING - TRACTION - BRAKING


Wheel positioning in width is affected by relatively few elements;

Front wheels are placed allowing for engine, structure, and steerangles...

Vehicle centerline


…rear wheels are placed allowing mostly for cabin space and/oralignment with front wheels

Vehicle centerline

Cabin Spaceprofile


Other vehicle requirements have to be brought in...→ fuel capacity as a consequence of desired range→ luggage space


... as well as safety considerations...→ crash collapse space→ occupant space for safety


... and legislation:→ visibility→ bumper placement


At this point, the vehicle’s main dimensions and proportions arepreliminarily set longitudinally, vertically,...→ wheelbase→ overhangs and therefore overall length→ ground clearance and overall height


…and laterally

→ front and rear tracks→ front and rear passenger access

Vehicle centerline

H-point

Front andrear headenvelopes

→ head space (roof width)→ overall width + door opening

Bodyaccess


THE BASICS NEEDED IN ORDER TO KICK OFF THESTYLING ACTIVITY ARE ESTABLISHED

→ we have the

VEHICLE PACKAGE!

car engineering concept design - mitweb.mit.edu/.../classnotes/14_conceptdesign.pdf · car...

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